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Biomedical subjects

J C Hendricks

Publications and source records attributed to J C Hendricks.

At least 55 records · Page 3Linked to original sources
PubMed1988

Discrimination of factors influencing biota of a stream receiving multiple-source perturbations.

Blaine Creek is a fifth-order stream located in eastern Kentucky that has been subject to contamination by oil brines, surface mining, and a coal fly ash settling pond discharge. Toxicity tests, effluent and receiving water chemical monitoring, and Blaine Creek benthic sampling were used to evaluate the effect of the ash pond effluent on the creek. Reproductive impairment of Ceriodaphnia was demonstrated at effluent concentrations ranging from 30 to 100%, but no instream impact on benthic invertebrates could be found at effluent flows that provided up to 65% of the creek's discharge. Correlation and regression analysis of physicochemical versus benthic monitoring data indicated that upstream oil brine contamination and scouring of the creek's predominately shifting sand substrate during rainfall events were the primary factors affecting the benthic fauna, and appeared to override potential effects from other sources. These results demonstrated the value of integrated field/laboratory investigations for effluent impact assessments.

Journal Article↗
PubMed1987

The English bulldog: a natural model of sleep-disordered breathing.

To establish a natural model of sleep-disordered breathing, we investigated respiration during wakefulness and sleep in the English bulldog. This breed is characterized by an abnormal upper airway anatomy, with enlargement of the soft palate and narrowing of the oropharynx. During sleep, the animals had disordered respiration and episodes of O2 desaturation. These were worst in rapid-eye-movement (REM) sleep, with most bulldogs having O2 saturations of less than 90% for prolonged durations. In contrast, control dogs never desaturated. In REM sleep, the bulldogs had episodes of both central and obstructive apnea, the latter being associated with paradoxical movements of the rib cage and abdomen. During wakefulness, the bulldogs were hypersomnolent as evidenced by a shortened sleep latency (mean of 12 min compared with greater than 150 min for controls). This animal model should facilitate studies of the natural history of the sleep apnea syndrome and its complications.

Animals↗
PubMed1986

Malignant tumors of the stomach.

A variety of malignancies may arise from the stomach, but the vast majority are adenocarcinomas. Despite a steady decline in the incidence of gastric carcinomas in the United States over the last 50 years, the overall prognosis remains dismal. Early diagnosis and an aggressive surgical approach provide the best hope of improving the outlook for patients with gastric cancer.

Adenocarcinoma↗
PubMed1986

Control of activity of the diaphragm in rapid-eye-movement sleep.

Respiration in rapid-eye-movement sleep (REMS) is known to be highly variable. The purpose of this study was to investigate the source of this variability and to determine which ordering principles remained operative in REM sleep. In unrestrained, naturally sleeping cats we recorded the electroencephalogram, electrooculogram, neck electromyogram, and diaphragmatic electromyogram (EMG) and computed its moving average (MAdi). As a reference, we first examined MAdi during "tonic" REMS, since breathing is fairly regular in this state. "Control" ranges for peak amplitude (PEMG), inspiratory time (TI), duration of postinspiratory inspiratory activity, expiratory time, and the calculated inspiratory slope (PEMG/TI) were determined by overlaying individual breath traces of the time course of MAdi during tonic REMS to form a composite tracing. Next, the time course of the EMG during individual breaths in slow-wave sleep (SWS) and a complete period of consecutive breaths in REMS (both tonic and phasic) were compared with this tonic REMS composite. The number of eye movements per breath was tabulated as an index of phasic activity. The inspiratory slopes during SWS and tonic REMS were similar. However, during phasic REMS, many breaths displayed either increases (excitation) or decreases (inhibition) in slope compared with the "typical" breaths seen in tonic REMS. The occurrence of these altered slopes increased with the frequency of phasic events. TI was inversely related to the slope of the EMG, which tended to minimize changes in PEMG.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Tracheal collapse in two cats.

Two cats examined bronchoscopically to discover the cause of tracheal collapse were found to have tracheal obstruction cranial to the collapse. Cats with this unusual sign should be examined bronchoscopically to ascertain whether there is an obstruction, as the cause in these 2 cats was distinct from the diffuse airway abnormality that causes tracheal collapse in dogs.

Animals↗
PubMed1985

Spontaneous rupture of hepatocellular carcinoma.

Spontaneous rupture of a primary hepatocellular carcinoma is an extremely rare event in the western hemisphere. Only a handful of single-case reports have been authored in the continental United States. A ruptured hepatoma carries a dismal prognosis and is usually beyond a "resection for cure" stage. In this report, two cases of spontaneously ruptured primary hepatocellular carcinoma are described. Both cases involved cirrhotic livers, and the tumor in each case was resected to attempt cure. One patient survived nearly 2 years; the other is alive and well at this time.

Aged↗
PubMed1985

Hepatic resection in cirrhotic patients.

Cirrhotic patients are at increased risk for the development of hepatocellular carcinoma, and surgical resection of the involved liver represents the only effective mode of therapy. The presence of cirrhosis significantly complicates hepatic resection. We describe the clinical course of a patient with ruptured hepatoma localized to the lateral segment of the left lobe. This case illustrates many of the problems encountered during hepatic resections in cirrhotic patients, which should be limited to segmental or subsegmental resections. Preoperative attention to bleeding and nutrition, meticulous intraoperative hemostasis, and postoperative management of any pulmonary complications, ascites, and renal or hepatic failure are mandatory for successful management.

Carcinoma, Hepatocellular↗
PubMed1985

Alternatives in the management of pancreatic cancer.

Pancreatic carcinoma is one of the most lethal malignancies seen in humans. If cure is to be effected, radical surgery for small lesions confined to the gland must be undertaken, but the cost in morbidity and mortality is high. An otherwise fit elderly patient should not be denied the small chance of cure because of age alone, but such a patient must be frankly appraised of the significant risks and limitations of resectional therapy. The Whipple procedure remains the standard operation for lesions of the head of the gland, but pre-existing severe diabetes and technical factors may dictate that a total pancreatectomy be performed. Patients with unresectable cancers who develop biliary or enteric obstruction should be bypassed internally if otherwise healthy. If frail or infirm from other organ failure, patients may be offered relief by a percutaneous decompression with minimal risk. Pain must be dealt with in all patients with celiac blocks or liberal use of analgesics. Adjuvant forms of therapy are experimental, costly in time and money, not without serious side effects, and should be advised cautiously in elderly patients.

Aged↗
PubMed1982

Different behaviors during paradoxical sleep without atonia depend on pontine lesion site.

Bilateral pontine tegmental lesions in cats release a state of paradoxical sleep (PS) without atonia that possess all other electrographic criteria of PS. PS without atonia has been previously considered as a unitary phenomenon, but the present work demonstrates that different behavioral syndromes result from different lesion placements. Five of 25 cats exhibited the minimal syndrome of increased proximal limb and head movements. The head was not raised; and coordinated behavior was not seen. The nuchal electromyogram (EMG) showed tone for 25-100% of such an episode. Selective destruction of the origin (n = 2) or caudally projecting fibers (n = 1), of the tegmentoreticular pathway released this minimal syndrome of unorganized limb and head movements. This pathway had previously been proposed to mediate atonia, but the present work demonstrates that additional damage is necessary to release tone completely as well as the elaborate behaviors discussed below. Eight cats raised their heads, righted their forequarters, and moved head, neck and forelimbs in movements resembling orienting, staring, reaching and attempting to stand. The lesions releasing such behavior were centered at P = 3.0, H = 2.0, V = -4.0, and damaged a region projecting to the superior colliculus. Two cats with slightly more ventral lesions did not exhibit the orienting behavior. Six cats demonstrated violent phasic behavior resembling attack punctuating tonic periods of quiet staring or searching movements. Attack resulted from damage extending rostroventrally into the midbrain at P = 2.0, H = 2.5, V = -4.5 (4/6) or from unilateral damage to a lateral pathway arising in the central amygdalar nucleus (2/6). In 4 cats, coordinated fore- and hindlimb activation resulted in locomotion during PS. Walking resulted from larger, more ventral lesions centered at P = 3.0, H = 2.0, V = -5.5. Considering the anatomy of the lesions in relationship to brain stem systems known to play a role in orienting, attack and locomotion, we conclude that inhibitory systems were damaged by these lesions and that PS without atonia is not simply a state during which neural activity of normal PS can be expressed behaviorally.

Amygdala↗
PubMed1981

A disorder of rapid eye movement sleep in a cat.

A young female cat with no neurologic abnormality during wakefulness was discovered to have violent motor activity during rapid eye movement sleep. Various characteristics of the disorder, which differentiated these episodes from epileptic seizures, suggested that the movements resulted from an exaggeration of phasic excitation during rapid eye movement sleep.

Animals↗
PubMed1981

The relationship of excessive exploratory behavior in wakefulness to paradoxical sleep without atonia.

The hypothesis that cats exhibiting paradoxical sleep (PS) without atonia are more active than normal in wakefulness was tested. To provide a quantitative measure of locomotor activity, 15 cats were subjected to an open-field test of activity for 5 one-hour or 10 half-hour sessions before and after placement of bilateral pontine tegmental lesions, which induce PS without atonia. Thirteen of the cats had PS without atonia and showed significant (p less than 0.05) increases in open-field activity, which was judged to be exploratory in nature, rather than aimless pacing. Increases ranged from 30-261%. In spite of the abnormal increase in antigravity muscle tone during PS postoperatively, hypertonia was not present during wakefulness. Of the 2 cats without elaborate behavior during PS, 1 had a significant decrease in activity. Its lesion may have damaged a lateral brainstem locomotor region. The same effect was obtained with unilateral damage of this region in 1 of 2 cats subjected to 2-stage operations. The results were used to develop the argument that peripheral motor inhibition during PS depends on suppression of a brainstem locomotor region in addition to direct inhibition of spinal motor neurons.

Animals↗
PubMed1980

Reflux of duodenal contents into the pancreatic duct of dogs.

Previously we demonstrated that postprandial duodenal pressure transiently exceeds pancreatic duct pressure in the dog. To determine whether this presure gradient causes reflux from the duodenum into the pancreatic duct, we provided each of five dogs with a permanent pancreatodochal catheter and three indwelling duodenal cutaneous catheters. 14C-PEG was infused through the proximal duodenal catheter; intraluminal pressures were monitored through the middle catheter at the level of the pancreatic duct orifice; and 15 cm abroad, duodenal contents were recovered from the third catheter. Fifteen-minute pooled samples were collected 1 hr preprandially and 2 hr postprandially from the pancreatic duct and duodenum and were analyzed for volume, lipase activity, and marker concentration. Reflux of duodenal contents occurred only in 10.8% of fasting periods but was observed in 38% of postprandial periods (p < 0.05). The total volume of duodenal content refluxed per 15 min approximated 0.1 ml and represented between 0.5% and 1% of total pancreatic volume flow and between 0.05% and 0.07% of total duodenal volume flow. Thus we have provided evidence that small amounts of duodenal contents may reflux into the pancreatic duct of dogs in our experimental model. This finding may be relevant to the pathogenesis of pancreatitis and pancreatic cancer.

Animals↗